Terragrunt source from specific git branch as a vairable

Question

I know that it is possible in terragrunt to add a git source reference to a specific branch as mentioned in another post.

But is it possible to set the branch based on something like a global variable?

So instead of

terraform {
   source = "git::https://git.repo.modules.git//src/modules/vpc?ref=develop"
}

something like

terraform {
   source = "git::https://git.repo.modules.git//src/modules/vpc?ref=${VAR_BRANCH}"
}

We develop on different branches and I don't want to change every source reference when merging things to another branch.

I also read about source mapping, but it seems to me that we also have to map every single source, or did I miss something?

Thank you very much & best regards

Answer 1

Your code example should work, i.e. if your variable is local the code snippet should look like this:

terraform {
   source = "git::https://git.repo.modules.git//src/modules/vpc?ref=${locals.branch}"
}

I also read about source mapping, but it seems to me that we also have to map every single source, or did I miss something?

Yes, that is correct. Unless you want to use the master branch.